What migratory pattern characterized offspring in the Central Sweden contact zone?

Hybrids usually adopted the route of one or the other parent subspecies.

In areas like Central Sweden where the two main migratory phenotypes breed adjacent to each other, hybridization occurs, creating a contact zone. Research into the genetic outcomes of this interbreeding revealed a critical finding regarding the inheritance of migratory behavior. Despite the mixing of genomes, the resulting hybrid offspring did not typically display a blended or intermediate migratory direction. Instead, the decision-making process appeared largely binary; the young birds generally adhered strictly to the specific migratory route established by one of their two parent subspecies. This non-intermediate pattern is hypothesized to be an evolutionary advantage, potentially reducing the mortality costs that might be associated with attempting a complex, mixed, or compromised migratory path, such as attempting to fly directly over large geographical barriers like the Mediterranean Sea.